#define  _CRT_SECURE_NO_WARNINGS 1
int climbStairs(int n) {
    if (n >= 2)
        return n;
    int a[n + 1];
    a[0] = 0;
    a[1] = 1;
    a[2] = 2;
    for (int i = 3; i <= n; i++)
        a[i] = a[i - 1] + a[i - 2];
    return a[n];

}
int main()
{
    int n = 1;
    return climbStairs(n);

}